1. Field of the Invention
This invention relates to briquetting presses. More particularly, this invention is directed to a ram-feeder for briquetting presses.
2. Description of the Prior Art
Briquetting presses for compacting paticulate material in complementary cavities disposed about the peripheries of a pair of cooperating rolls have been in use for many years. As new applications for such briquetting presses develop, the structure and operation of the presses have to be modified.
The basic elements of briquetting presses are a pair of cooperating rolls, means for feeding particulate material into the nip of the rolls, means for rotating the rolls and means for biasing the rolls together. Each new application of a briquetting press requires variation in the structure or operation of these elements. While determination of suitable roll geometry is of primary concern, providing means for feeding particulate material into the nip of the rolls is a significant design concern. For each application, the feeder must meter the proper mass of paticulate material into each pair of complementary cavities on the peripheries of rapidly rotating rolls.
In early presses which were used primarily for forming or shaping materials, the problem of feeding the material was not severe; simple gravity-type feeders were generally adequate. For each tool geometry, however, there is a maximum increase in density which can be imposed on the material being formed between the rolls.
As the requirement for briquettes of greater density arose, the density-increasing effect of the rolls was supplemented by a screw or auger-type feeder which tended to increase the material density as it was fed into the nip of the rolls. The common use of screw-type feeders in briquetting presses today attests to their success for certain applications.
There have developed, however, many new applications for briquetting presses where screw-type feeders have proved impractical or a source of constant maintenance. The briquetting of high temperature or abrasive materials has presented particular problems. These materials have caused severe wear of screw-type feeders. Even though screw-type feeders have been made of expensive, exotic metals which resist the effects of high temperature and abrasive materials, frequent maintenance and replacement of scrrew feeders remain a problem. These problems with screw feeders have placed limits on the effective increase of density which may be provided by screw feeders when used to briquette high temperature or abrasive materials.
The present invention overcomes the problem by providing a feeder which greatly reduces the abrasive wear caused by the sliding or relative motion between the feeder and the particulate material being briquetted.
In particular, this invention is directed to an axially reciprocating ram feeder which pre-compresses particulate material into the nip of the rolls. In addition to reducing wear-causing abrasion, by varying the rate of reciprocation or length of stroke of the ram depending upon the rate of rotation of the rolls or roll geometry, the invention provides means for varying the amount of pre-compression obtained.
The ram feeder of the invention is also designed to be installed in the space occupied by screw-type feeders on existing briquetting machines. Thus, the advantages of the ram feeder may be obtained without having to invest in a new briquetting press.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.